Early occlusal caries detection using targeted fluorescent starch nanoparticles

Surface porosity of enamel white spot lesions and penetration of fluorapatite nanocrystals into their subsurface: proof-of-concept study

OBJECTIVES

In this study, we used atomic force microscopy (AFM) to quantify the size of surface pore apertures of enamel white spot lesions and then demonstrated the penetration of fluorapatite nanocrystals (nFA) into the subsurface of these lesions.

METHODS

For the porosity study, enamel lesions were created on three sound human teeth using a demineralizing gel for 8 days. The interface between sound enamel and the artificial lesion was analyzed by AFM. To visualize the penetration of nFA tagged with a calcium-binding fluorophore (Fluo-4) into the subsurface of white spot lesions, we used two-photon microscopy. Sixteen extracted human teeth with either active, natural, or in vitro-created carious lesions in enamel were randomly divided into three groups. The teeth were treated for 2 min with either a suspension of tagged nFA crystals, Fluo-4 alone, or deionized water, and left for 30 min before being washed with distilled water and examined microscopically.

RESULTS

A greater concentration of surface pores with larger areas was observed on the in vitro demineralized enamel (29 % of pores greater than 1.0 µm2) when compared with the adjacent sound enamel (8 % of pores greater than 1.0 µm2) (p=0.012, Fisher exact test). In vitro and natural lesions treated with tagged nFA showed fluorescence at depths ranging from 50 to 170 µm, demonstrating penetration of the nFA into the lesion subsurface. The lesions treated with Fluo-4 alone with no crystals showed mostly surface fluorescence (restricted to the outer 25 µm), while those treated with deionized water showed minimal (restricted to the outer 20 µm) to no fluorescence.

CONCLUSION

We have demonstrated the use of AFM to quantify the surface pore apertures and two-photon microscopy to visualize nFA crystals in the subsurface of non-cavitated enamel lesions.

CLINICAL SIGNIFICANCE

The restoration of the subsurface of non-cavitated caries lesions is a clinical challenge. This study demonstrated that a 2 min application of nFA could penetrate through the surface apertures of non-cavitated enamel lesions into their subsurface.

Detection, Diagnosis, and Monitoring of Early Caries: The Future of Individualized Dental Care

Dental caries remains a significant global health issue. It was highlighted by the World Health Organization's 2022 reports that despite the efforts and scientific advancements in caries detection and management, the situation has only marginally improved over the past three decades. The persistence of this problem may be linked to outdated concepts developed almost a century ago but are still guiding dentists' approach to caries management today. There is a need to reconsider professional strategies for preventing and managing the disease. Contemporary dentistry could benefit from embracing new concepts and technologies for caries detection and management. Dentists should explore, among others, alternative methods for caries detection such as optical-based caries detection. These tools have been established for over a decade and they align with current disease understanding and international recommendations, emphasizing early detection and minimally invasive management. This narrative review presents the current state of knowledge and recent trends in caries detection, diagnosis, monitoring, and management, offering insights into future perspectives for clinical applications and research topics.

Detection of artificial enamel caries-like lesions with a blue hydroxyapatite-binding porosity probe

OBJECTIVES

This in vitro study investigated the ability of a blue protein-based hydroxyapatite porosity probe to selectively detect artificial enamel caries-like lesions of varying severities.

METHODS

Artificial caries-like lesions were formed in enamel specimens using a hydroxyethylcellulose-containing lactic acid gel for 4/12/24/72 or 168 h. One untreated group was used as a control. The probe was applied for 2 min and unbound probe rinsed off with deionized water. Surface color changes were determined spectrophotometrically (L*a*b* color space) and with digital photography. Lesions were characterized using quantitative light-induced fluorescence (QLF), Vickers surface microhardness, and transverse microradiography (TMR). Data were analyzed using one-way ANOVA.

RESULTS

Digital photography did not reveal any discoloration in unaffected enamel. However, all lesions stained blue with color intensity positively correlated with demineralization times. The color data reflected similar trends: lesions became significantly darker (L* decreased) and bluer (b* decreased), while overall color differences (ΔE) increased significantly after probe application (4-h lesion, mean±standard deviation: ΔL*=-2.6 ± 4.1/Δb*=0.1 ± 0.8/ΔE=5.5 ± 1.3 vs. 168-h lesion: ΔL*=-17.3 ± 1.1/Δb*=-6.0 ± 0.6/ΔE=18.7 ± 1.1). TMR analysis revealed distinct differences in integrated mineral loss (ΔZ) and lesion depth (L) between demineralization times (4-h lesion: ΔZ=391±190 vol%min × µm/L = 18.1 ± 10.9 µm vs. 168-h lesion: ΔZ=3606±499 vol%min × µm/L = 111.9 ± 13.9 µm). QLF and microhardness were also able to differentiate between demineralization times. L and ΔZ strongly correlated (Pearson correlation coefficient [r]) with Δb* (L vs. Δb*: r=-0.90/ΔZ vs. Δb*: r=-0.90), ΔE (r = 0.85/r = 0.81), and ΔL* (r=-0.79/r=-0.73).

CONCLUSION

Considering the limitations of this study, the blue protein-based hydroxyapatite-binding porosity probe appears to be sufficiently sensitive to distinguish between unaffected enamel and artificial caries-like lesions.

CLINICAL SIGNIFICANCE

Early detection of enamel caries lesions remains one of the most critical aspects in the diagnosis and management of dental caries. This study highlighted the potential of a novel porosity probe in detecting artificial caries-like demineralization by objective means.

Evaluation of a novel caries detecting oral rinse

AIM

LumiCare™ Caries Detection Rinse (LC Rinse), a starch-based rinse, illuminates active initial caries (positive response) using dental curing light, thus augmenting the dentist's visual examination. This clinical study investigated if active caries as assessed by the International Caries Detection and Assessment System (ICDAS) were more likely to have positive LC Rinse response than sound surfaces and inactive caries.

METHODS

25 subjects participated in the study. Caries was assessed on selected teeth and the entire dentition, firstly using ICDAS and then by fluorescence evaluation after LC Rinse application. Data were statistically analyzed using Diagnostic Odds Ratio (OR) and Chi-square test X² (α = 0.05). Sensitivity (Se), specificity (Sp), and Diagnostic accuracy (DA) were calculated.

RESULTS

With selected teeth, active caries were 638.6 times (60.05 with full dentition) more likely to have positive LC Rinse response than sound surfaces and inactive caries combined (X², p < 0.01) and 191.67 times (18.35 with full dentition) than inactive lesions only (X², p < 0.01). With combined sound surfaces and inactive caries, Se, Sp, and DA of LC Rinse assessment were 0.94, 0.98, and 0.96 respectively.

CONCLUSIONS

LC Rinse can distinguish between active caries, inactive caries and hypomineralization, and can augment caries detection with high sensitivity, specificity, and diagnostic accuracy.